1. Technical Field
The present disclosure relates to surgical instruments, e.g., surgical fastener or stapler apparatus and, more particularly to circular surgical staplers for performing surgical procedures, including but not limited to rectal mucosectomies, rectal anopexies, anastamoses, hemorrhoidectomies, or the like. In addition the present disclosure relates to methods of performing such surgical procedures.
2. Background of Related Art
Various types of surgical fastener applicators and/or staplers are known for the application of fasteners or staples to tissue in order to join adjacent tissues. For example, it is known to use various types of staplers in gastric and esophageal surgery, in both classic or modified gastric reconstructions performed end-to-end, end-to-side, or side-to-side, as well as for performing a hemorrhoidectomy.
Hemorrhoids are a mass of dialated veins in swollen tissue at the margin of the anus or nearby within the rectum. Typically, hemorrhoids are caused by chronic straining for example from constipation and/or childbirth. The plexus of vascular tissue beneath the epithelial lining of the anal canal is called the corpus cavemosus recti or anal cushion. The plexus connect arteries to veins without intervening capillaries thus creating the vascular component of the anal cushions. These arteriovenous channels control the size of the anal cushions by regulating the blood volume flowing through them. Chronic straining damages the submucosal fibroelastic connective and the anal cushions protrude into the anal canal and may produce painless bleeding (first degree hemorrhoids). Prolapsed hemorrhoids lying outside the anal canal may become strangulated by the internal sphincter activity with possible thrombosis of the venous plexus (fourth-degree hemorrhoids). This condition may result in gangrene with the risk of abscess formation.
Hemorrhoids can be of two types, external and internal. A ribbed dentate line is located about 2.5 to 3 cm in from the exterior of the anus and marks the change from the anus to the rectum. Hemorrhoids are found in the anal area before this line. Internal hemorrhoids generally are found in the rectal area before this line and external hemorrhoids generally are external of the anal ring. Internal hemorrhoids are generally formed from arteriovenous anastomoses or connections that reside in a submucosal space within the wall of the rectum, approximately 2.5 to 5 cm in from the exterior of the anus. Due to its proximity to the anus, internal hemorrhoids can protrude from the wall of the rectum in either one localized area, more than one localized area, or circumferentially around the rectum and in certain severe cases, the internal hemorrhoids can protrude out of the anus.
A wide variety of surgical methods have been suggested for the treatment of severe internal hemorrhoids. One method is a closed hemorrhoidectomy. According to this method a retractor is inserted into the anus to obtain access to a hemorrhoidal site. The surgeon then clamps the hemorrhoid with alligator clamps, ligates the vessels, and dissects the hemorrhoid from the rectal wall with a scalpel or scissors. Once the hemorrhoid is removed, the surgical site is sutured closed. The retractor is then rotated to another position and the remaining hemorrhoids are treated in a similar manner until all of the hemorrhoids have been removed.
Another method for the removal of internal hemorrhoids is an open hemorrhoidectomy. According to this procedure, rather than using a retractor, the anus is gently dilated with two fingers and forceps are placed at the mucocutaneous junction of each primary hemorrhoid. The hemorrhoids are pulled down and a second forceps is applied to the main bulk of each hemorrhoid to produce “a triangle of exposure”. Next, the clamped, hemorrhoid is dissected from the sphincter muscle and is dissected proximally as far as the pedicles and then ligated or tied. Unlike the closed procedure, the wound is not sutured closed, but is left open with a light dressing applied to the wound.
Yet another hemorrhoidectomy procedure involves excising hemorrhoidal tissue above the dentate line and excising and suturing the redundant rectal mucosa to the anoderm. This procedure is particularly used in conjunction with circumferential hemorrhoids.
In a paper by Dr. G. Allegra entitled “Particular Experience with Mechanical Sutures: Circular Stapler for Hemorrhoidectomy,” presented to the 1.sup.st. National Conference of the Italian Viscerosynthesis Association in May 28-30, 1989, and published in GIORN Chir. Vol. 11-No. 3-pp 95-97, March 1990, Dr. Allegra disclosed a simpler and faster method for performing a hemorrhoidectomy. The paper discloses the use of a conventional circular stapler to perform a hemorrhoidectomy on second and third degree hemorrhoids. According to the procedure detailed by Dr. Allegra, the anus is dilated to place a continuous submucosal circle of sutures at the base of the pectinate or dentate line. Next, the end effector of a conventional circular stapling instrument is opened and placed into the anus of a patient such that the anvil assembly of the stapling end effector is distal of the suture ring and the stapling head assembly (of the stapling end effector) is proximally outside of the patient. This placement enables the surgeon to reach within the anus in order to grasp the loose ends of the suture. The loose ends of the suture are then pulled to draw the circle of suture closed and to draw the hemorrhoidal tissue in around the anvil shaft which connects the anvil to the stapling head assembly of the circular stapling instrument. Next, the surgeon closes the anvil upon the hemorrhoidal mass and the stapler is fired to perform the hemorrhoidal transection. Once fired, the circular stapling instrument is removed from the anus with the transected hemorrhoids captured within.
One limitation of Dr. Allegra's procedure is that the stapling head assembly must be placed proximally outside of the patient to enable the surgeon to grasp the loose ends of the suture and to draw the suture out of the anus through a gap between the anus and the stapling head assembly. The gap between the anus and the stapling head assembly is needed to permit withdrawal of the suture from the anus and thus limits the depth that the stapling end effector can be placed into the anus. Using Dr. Allegra's procedure, if the hemorrhoids are located deeper into the anal canal, as in the case of internal hemorrhoids, the stapling head assembly enters the anus and effectively blocks the surgeon from accessing the loose ends of the suture.
An additional limitation of Dr. Allegra's procedure is the amount of hemorrhoidal tissue that can be drawn into the stapling end effector of a conventional circular stapling instrument. Hemorrhoids are drawn into and around an anvil shaft (connecting the open anvil assembly to the stapling head assembly) by tightening a continuous loop of suture placed below the dentate line. This action draws the hemorrhoids around the anvil shaft but does not draw the hemorrhoids into the inner chamber of the stapling head assembly. This limits the amount of hemorrhoidal tissue that can be brought into the stapling end effector and the surgeon may remove only part of a hemorrhoid.
U.S. Pat. No. 6,083,241, to Longo et al. also discloses a method for removing internal hemorrhoids from a patient using a circular stapler. A suture is placed into or above the internal hemorrhoids of the patient. A needle hook is employed to grasp the suture and withdraw the suture through a passageway in the stapling head assembly and out of the casing of the stapling head assembly. The circular stapling instrument is closed and then fired in order to staple and cut the hemorrhoidal tissue and the stapling instrument is removed from the patient to remove the tissue from the patient.
A significant drawback of both the Dr. Allegra and the Longo et al. procedures is the complexity of the procedures. Each calls for the hemorrhoidal tissue to be sutured, prior to stapling and cutting. This significantly increases the time of performing the procedure and in turn increases the potential for complications and the potential for trauma to the patient. As described above, each procedure generally requires that a purse string type suture be first sewn into the tissue by using a retractor to expose a portion of the tissue; suturing the exposed portion of the tissue; repositioning the retractor adjacent the sutured portion and repeating these steps around the circumference of the rectal cavity until the entire tissue has been sutured.
Thus, the need exists for surgical staplers and/or apparatus which are less complex and can more quickly perform a surgical procedure than existing surgical staplers. In addition, the need exists for staplers and/or apparatus which reduce the trauma experienced by the patient during the surgical procedures described above. Further, the need exists for methods of performing the above described surgical procedures which are less complex and less time consuming than existing methods of performing the same.